1. Field of the Invention
The present invention relates to a keyboard device for an electronic keyboard instrument applied e.g. to an electronic piano, and more particularly to a key support structure for pivotally supporting keys.
2. Description of the Related Art
Conventionally, there has been known a keyboard device for an electronic keyboard instrument, disclosed in Japanese Patent Publication No. 3085033. This keyboard device is applied to a pedal keyboard for an electronic musical instrument, and comprises a frame and a plurality of keys pivotally supported on the frame and arranged side by side in a left-right direction. Each of the keys extends in a front-rear direction and has a rear end thereof formed with a pivot that extends in the left-right direction and has a circular cross section. Further, the frame has a rear end formed in a manner covering the rear ends of the respective keys from the rear to above, and inside the rear end of the frame, there are formed a pair of left and right support portions for supporting the pivot of each key. Each of the support portions has an arcuate curved surface in the shape of a quarter circle in side view, and is configured to support the pivot of an associated key obliquely from the rear and above by the arcuate curved surface. Further, between the pair of support portions is attached a pivot bearing piece that cooperates with the support portions to support the pivot of the associated key. The pivot bearing piece has an arcuate curved surface in the shape of a half circle in side view, and is configured to support the pivot of the key from below by the arcuate curved surface.
In the keyboard device constructed as above, the three arcuate curved surfaces of the two support portions and the pivot bearing piece on the frame side function as a bearing for supporting the pivot of the associated key. With this arrangement, when stepped on to operate for musical performance, each key of the keyboard device performs relatively stable pivotal motion about the axis of the pivot of the rear end thereof.
In the keyboard device, work for mounting each key to the frame during assembly of the keyboard device is performed as follows: First, a key is set on the frame such that the pivot thereof is positioned close to the arcuate curved surfaces of the two support portions of the frame. Then, the pivot bearing piece is inserted from below into a guide groove formed between the two support portions. Thereafter, the pivot bearing piece is slid upward along the guide groove, until it is stopped by the lower end thereof being snap-coupled to the edge of a keybed integral with a partition plate provided inside the frame. Thus, the pivot bearing piece is fixed to the frame, and the key is mounted to the frame.
In this keyboard device, although each key can be securely mounted to the frame in a pivotally movable manner, the work for mounting the keys to the frame during assembly of the keyboard device is complicated. More specifically, in order to mount each key to the frame, as described above, it is required to insert the pivot bearing piece into the guide groove between the two support portions from below, for the frame on which the key is set. In this case, the guide groove is surrounded on the front, rear, left, right, and top sides thereof by the rear end of the frame, the set key, and the partition plate, and so forth, which makes it difficult for a worker to view the position of the guide groove. For this reason, in the case of inserting the pivot bearing piece into the guide groove, the worker has to look into the guide groove from below the frame or grope for the guide groove to confirm the position of the same. Particularly in the case of mounting the pivot bearing pieces one by one for the respective keys, the work therefor is very complicated, and hence it takes much time and labor for assembling the keyboard device. Further, the pivot bearing piece snap-coupled to the keybed is difficult to remove due to its construction, which makes it difficult to disassemble the keyboard device into the frame and the keys e.g. when disposing of the electronic musical instrument.